If AWS actually tried to abuse its power, it would really damage the tech industry. Tech companies would see the risk and start treating the cloud as rented machines (EC2), and stop realizing all the benefits of their provider managing a complex system on their behalf.
If I were AWS, I'd willingly write into contracts that costs can go up no faster than the PPI + 5%, barring some sort of force majeure. Hardware gets cheaper, so I'd expect costs to come down, but this essentially "we're not going to screw you" clause.
If AWS tried to abuse its power, people would switch to another CSP.
While certainly, the shift would not be easy, but if AWS increased their prices enough, it could still be a savings in the long run.
EDIT: On the other hand, publicly traded companies are often extremely short-sighted because they have to make those quarterly reports, so maybe they would be unwilling to spend $X over the course of a year in order to save $X every year after that.
Such a platform should be a co-op owned by all the users, designed for the public good. It really is almost like a piece of infrastructure.
But AWS is a business, and businesses are there to make money. They are there to extract as much money as possible from users. I doubt they'll ever do a big change like Unity, but I bet they end up with a slow boil of raising prices.
If I were AWS, I'd willingly write into contracts that costs can go up no faster than the PPI + 5%, barring some sort of force majeure. Hardware gets cheaper, so I'd expect costs to come down, but this essentially "we're not going to screw you" clause.